System and apparatus for purging absorptive materials used in the removal of contaminates from an aqueous medium

ABSTRACT

Methods, systems and apparatus are provided for purging an adsorptive material of entrapped particulates. Methods, systems and apparatus rely upon a reverse loop for reversing the flow of medium within an adsorption material, allowing particulates caught within the adsorption material to be preferentially moved through and out of the adsorption material.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims benefit under 35 U.S.C. §119(e) to U.S.Patent Application No. 60/737,159, filed Nov. 15, 2005 and incorporatedherein by reference in its entirety. The present disclosure is relatedto U.S. Patent Application No. 60/515,921 filed Oct. 29, 2003 andentitled DYNAMIC UP-FLOW ZEOLITE SYSTEM, which is herein incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The invention generally relates to methods, systems and apparatus forremoval of a contaminate from an aqueous medium. More specifically, theinvention provides methods, systems and apparatus for minimizingback-pressure in an adsorption material constrained within a housing,the adsorption material used to remove contaminates from a flowingaqueous medium.

b. Background Art

Cities and towns throughout the world depend on having clean potablewater. The dependence on clean potable water has increased as thepopulation of the world has increased, especially as industrial use offresh water resources have become commonplace. Increased industrial useof fresh water resources has resulted in a corresponding deteriorationof water quality throughout the world, due partly to industrial relatedrelease of contaminates into the water. In addition, contaminates arealso naturally present in various fresh water resources, for example,high uranium content in fresh water resources throughout areas ofColorado, New Mexico and Texas.

The decrease in water quality is contravening to the world's increaseddependence on clean potable water supplies, requiring a concerted efforttoward both minimizing the release, and removing existing contaminates,from water supplies throughout the world (whether the contaminates arenatural or released as industrial pollution).

Conventional water treatment facilities are often equipped withspecialized systems for removal of specific contaminates from a watersupply. For example, water treatment facilities can be equipped tocontact the water supply with an affinity material having sorptivequalities toward a specific contaminate. Typically, these sorptivematerials are constrained in a column, or other like housing, thatreceives the water source, treats the water source, and passes the watersource back to a traditional water treatment facility.

A number of target contaminates can be removed from a water source whencontacted to a sorptive material. For example, removal of uranium froman aqueous medium has previously been described in U.S. ProvisionalPatent Application No. 60/619,369, filed Oct. 15, 2004.

Conventionally, removal of contaminates using sorptive materials isoften accomplished through the use of down- or up-flow media adsorption.Aqueous medium is released onto the adsorptive material and flowsthrough the material in a given direction. One problem facing the watertreatment industry is the clogging of these large volume housing unitswith suspended particulates in the aqueous medium. Clogged adsorptionmaterial leads to increased pressures required to “force” the waterthrough the adsorption and particulate material. The clogging ultimatelyresults in more costly water treatment and shut down to either replacethe adsorption material or to perform costly backwash, where the aqueousmedium and clogging particles are forced through and out of the columnin the opposite direction of normal flow, carrying the particulates outof the column for disposal.

In particularly problematic cases, the particulates have a low level ofradioactivity, for example, the particulates may have a low amount ofuranium. When radioactive particulates are concentrated within anadsorption material they often must be disposed of at a low levelradioactive repository. In contrast, under normal flow throughconditions, the radioactive material in the particulates is often atsuch low concentrations, that it is allowed to pass onto the end user ofthe water, to a sewer system, or to a water treatment facility.

Against this backdrop the present invention was developed.

BRIEF SUMMARY OF THE INVENTION

The present invention provides methods, systems and apparatus forcontacting an adsorption material with a continuous flow of aqueousmedium for the removal of target contaminates from the aqueous medium.Adsorption material is constrained within a housing, typically acompartmentalized column, and aqueous medium is passed through thehousing in an up-flow direction. Aspects of the invention limitback-pressure build-up from within the housing by preferentiallyeliminating particulates and other clogging materials from theadsorption material. Aspects of the invention provide a significant costand time benefit over standard back-wash procedures used to dislodgeparticulates from within an adsorption material.

In one aspect of the invention, methods are provided for limitingback-pressure within a column by providing an environment within thecolumn that preferentially causes particulates, located in most aqueousmedium sources, trapped within the adsorption material to be movedtoward, and ultimately out, of the column. The methods include stoppingthe normal up-flow direction of the aqueous medium through the columnwhen a pre-determined level of back-pressure has built up within thecolumn, thereby allowing the adsorption material and particulates tosettle in the column. Stopping the up-flow of the aqueous medium withinthe column allows the adsorption material to settle within the column,where particulates are typically of a lesser density than the adsorptionmaterial, thereby settling slower and preferentially moving toward theoutlet end of the adsorption material. The flow of the aqueous medium isthen reversed and circulated within the compartments of the column toagitate and preferentially further move particulates to the top side ofthe adsorption material. The reversal of the aqueous medium provides aloop of flow from the middle inside compartment of the column, to theoutside of the column, to the top inside of the column and then backdown to the middle inside of the column. This loop of flow causing theparticulates to preferentially settle and concentrate on the outlet sideof the adsorption material. An alternative slow start can also be usedto expand the adsorption material in the up-flow direction, removingparticulates and allowing particulates within the top region of theadsorption material to also be removed from the column. Note thataspects of the present invention provide a method that preferentiallymoves particulates from the inlet of the column to the outlet of thecolumn without major concentrations of particulates being trapped in theadsorption material.

In another aspect of the invention, a column is provided having anintegrated reversal loop built into the column. The reverse loopincludes a pump or other like device for reversing the flow of the fluidwithin the column, a series of piping on the outside of the column formoving aqueous medium from the middle of the column to the top of thecolumn and a shut off valve for stopping the back-wash of the aqueousmedium out the inlet of the column (especially when the fluid isreversed toward the inlet). Other aspects of the invention providesystems having integrated purging columns and filters for passingparticulates found in an aqueous medium from the feed to the dischargeto a sewer or other like discharge spot.

These and various other features and advantages of the invention will beapparent from a reading of the following detailed description and areview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative side view of a purging column showing an inletand an outlet of the column in accordance with one embodiment of thepresent invention.

FIG. 2 is an illustrative top view of a purging column showing an inlet,an outlet and a reverse loop in accordance with one embodiment of thepresent invention.

FIG. 3A shows a cross sectional view along line 3-3 of FIG. 2.

FIG. 3B is an illustrative cross sectional view of a purging columnhaving two compartments, each compartment constraining a portion ofadsorption material and showing a reverse loop, the purging column inaccordance with one embodiment of the present invention.

FIG. 4 is a cross sectional view along line 4-4 of FIG. 3A.

FIG. 5A is a cross sectional view along line 5-5 of FIG. 3A.

FIG. 5B is an exploded view of one opening in the divider shown in FIG.5A.

FIG. 6 is an illustrative cross sectional view along line 6-6 of FIG.5B.

FIG. 7 is an illustrative perspective view of one opening in the dividershown in FIG. 5A in accordance with one embodiment of the presentinvention.

FIG. 8 is an illustrative perspective view of a purging columndistribution pipe in accordance with one embodiment of the presentinvention.

FIG. 9 shows a flow diagram for purging a column operating in an up-flowdirection in accordance with one embodiment of the present invention.

FIG. 10 illustrates a cross sectional view of normal up-flow of aqueousmedium through a purging column having two vertically stackedcompartments in accordance with one embodiment of the present invention.

FIG. 11 illustrates a cross sectional view of stop-flow of aqueousmedium in a purging column having two vertically stacked compartments inaccordance with one embodiment of the present invention.

FIG. 12 illustrates a cross sectional view of a pulsed back-flow ofaqueous medium using a reverse loop in a purging column having twovertically stacked compartments in accordance with one embodiment of thepresent invention.

FIG. 13 illustrates a cross sectional view of re-start of normal up-flowof aqueous medium through a purging column having two vertically stackedcompartments in accordance with one embodiment of the present invention.

FIG. 14A is a schematic diagram showing one system embodiment inaccordance with the present invention.

FIG. 14B is a schematic diagram showing an alternative system designembodiment in accordance with the present invention.

FIG. 15 is an illustrative perspective view of a two column system inaccordance with an embodiment of the present invention.

FIG. 16 is an illustrative top view of a two column system as shown inFIG. 15 in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following definitions are provided to facilitate understanding ofcertain terms used frequently herein and not meant to limit the scope ofthe present disclosure:

“Aqueous medium” or “aqueous media” refers to water, e.g., drinkingwater, or any liquid having water as a constituent. In some cases,aqueous medium can comprise a contaminate in need of removal, e.g., anaqueous medium can be ground water contaminated with U²³⁸ or radium. Inaddition, aqueous medium typically contains some level of suspendedparticulates or solids.

“Back-pressure” refers to pressure that exists within the housing orcolumn used to constrain the adsorptive material of the presentinvention. The pressure within the column is a reflection of how muchforce is required to move the aqueous medium through the adsorptivematerial of the column. For purposes of the present invention, anincrease in back-pressure refers to any increase of pressure within thecolumn that occurs once a column has been packed with an adsorptivematerial and aqueous medium run through the column for some length oftime, e.g., if a column has an initial pressure of 2-3 pounds/in², anincrease in back-pressure is when the pressure required to move theaqueous medium through the adsorptive material is above 3 pounds/in²,for example 5 pounds/in². For purposes of the present invention,increased back-pressure within a column is generally caused by cloggingof the adsorptive material with particulates from within aqueous medium.

“Feed” refers to an aqueous medium before entering a column or system ofthe present invention. For example, a feed may be a ground water supplyjust prior to entering a column designed in accordance with the presentinvention.

“Particulate” refers to materials suspended in aqueous medium beingtreated by the methods and systems of the present invention.Particulates typically clog filters or adsorption-based materials, e.g.,resins, during flow of the aqueous medium through the adsorptionmaterial of the present invention. Particulates can also be radioactive,for example, suspended particulates having a low level ofradionucleotides incorporated therein.

“Adsorb” and “absorb” refer to the same basic principle of one substancebeing restrained by another substance. The process can includeattraction of one substance to the surface of another substance or thepenetration of one substance into the inner structure of anothersubstance. For example, the present invention contemplates that resinscan either adsorb or absorb uranium from an aqueous medium, i.e., forpurposes of the present invention the two terms are interchangeable.Other terms may also be used to describe this interaction and are alsowithin the scope of the present invention, these terms include:sorption, binding, trapping, etc, all of which for purposes of thepresent invention are interchangeable with adsorption.

“Adsorption material” or “adsorptive material” refers to ion exchangeresins, zeolites (natural and synthetic), activated media (granularactivated carbon and activated alumina) and other like materials thathave adsorptive characteristics for contaminates within an aqueousmedium. Different types of adsorptive materials are used for the removalof different contaminates, i.e., have different adsorptivecharacteristics for different contaminates. In addition, differentadsorptive materials have different density and shape i.e.,sedimentation/settling parameters, within a given aqueous medium,thereby different adsorption materials have different characteristicswithin the context of the present invention. Adsorptive materials of thepresent invention, as used in the context of the present invention, havea higher settling rate than the majority of particulates in an aqueousmedium treated by that adsorptive material, but are also dispersedagainst gravity in the direction of the up-flow during normal operationsof apparatus of the invention. Exemplary adsorption materials includesynthetic anion and cation exchange resins and zeolites.

“Up-flow” refers to the direction that aqueous medium flows through anadsorptive material constrained in a housing of the present invention.Up-flow is generally in a direction that contravenes gravity, ascompared to down-flow, which at least partially relies on gravity topass the aqueous medium over the adsorption material constrained withina housing. Up-flow of aqueous medium generally requires a certain amountof pressure to move the medium through the adsorption material againstgravity. Dependent on the density of the adsorption material and theflow rate of the aqueous medium, up-flow aqueous medium can suspend theadsorption material toward the outlet end of the housing. In preferredembodiments of the present invention, up-flow refers to a sufficientflow of aqueous medium to force an adsorption material to the outlet endof the housing.

Embodiments of the present invention provide methods, systems andapparatus for limiting back-pressure within an adsorption materialcontaining housing, where the adsorption material containing housing isused for removal of contaminates from an aqueous medium in a timely andeffective manner. Embodiments of the present invention are useful in thecontext of continuous flow of an aqueous medium through a housing thatconstrains a useful amount of adsorption material. The adsorptionmaterial has an affinity for certain target contaminates found withinthe aqueous medium, for example, an strong base anion exchange resin foruranium. Aqueous medium flows through the housing in generally anup-flow direction, i.e., contravening, or flowing against, some or allof the effects of the downward force of gravity. The methods, systemsand apparatus are generally useful in numerous different housing shapesor sizes, numbers of connected housing units, i.e., one, two, three,etc, and types of adsorption materials constrained within the housingunits (see below). Note that for purposes of the present invention, thefollowing embodiments will be described with regard to a column,although other housing units can be also be used. Description of acolumn unit is not meant to limit the present invention to columns, butsimply as an illustrative unit that can be used to constrain adsorptionmaterial in the context of the present invention.

Embodiments of the present invention provide for the reduction of backpressure within an adsorption material containing column throughreduction of particulates trapped within the adsorption material. Inmost embodiments, methods, systems and apparatus are provided topreferentially release particulates from the adsorption material for thedischarge of the aqueous medium with an amount of particulatespreviously trapped in the adsorption material, thereby avoiding a timelyand expensive back-wash and potential manual disposal of built-upparticulates at a disposal site from the adsorption material.

Purging Column

The present invention provides a column for the contact between anadsorption material and a continuous or discontinuous flow of aqueousmedium, the column adapted for fast and efficient particulate purgingand ensuing reduction in the back-pressure within the column. Inaddition, the invention provides efficient methods, systems andapparatus for avoiding the time and cost of disposing concentratedamounts of particulates that have been trapped within an adsorptionmaterial.

Referring to FIGS. 1-8, column embodiments of the present invention areshown, each column 100 generally having an input end 102, a middleportion 104, and an output end 106. Columns 100 can be singular andconstrain one set amount of adsorption material (see FIGS. 14B, 15 and16) or define two or more compartments 108, 110 within, each compartmenthaving a set amount of adsorption material (for example, FIGS. 1-8).Compartments within one column are generally stacked on top of eachother due to the up-flow direction of the aqueous medium, eachcompartment separated by a screen and optionally a (see below and FIG.5A). Note that additional compartments can be included within a column,dependent on the capacity, aqueous medium flow rate, size of thecompartment, etc.

Referring to FIG. 1, a side view of a purging column 100 in accordancewith the present invention is shown. The column generally has an inlet114, a pair of stacked compartments 108, 110 separated by a divider 128and screen 112, an outlet 116, and a pressure release valve 118. Aqueousmedium, or the feed, enters the column at the inlet 114 located at theinput end 102 of the column 100. The aqueous medium moves through thefirst 108 and then second 110 compartments and is discharged out of aseries of one or more outlet pipes 116. In the process of moving throughthe two compartments, contaminates within the aqueous medium are removedvia constrained adsorption material within each of the two compartments(see below and not shown in FIG. 1). A pressure valve 118 acts as apressure release when the pressure within the column reachesunacceptable levels. In an optional embodiment, a filter unit 120 isshown receiving the discharged aqueous medium for filtration ofdischarged particulates and/or adsorption materials from the columnduring operation.

FIG. 2 depicts a top view of a column 100 (for example as shown inFIG. 1) in accordance with the present invention, providing a view of areverse loop 122 for reversing or purging the adsorption material in thetwo compartments 108, 110 when the normal up-flow direction of thecolumn is interrupted. The reverse loop 122 has vertical piping forcirculating aqueous medium and particulates from the lower or firstcompartment of the column to the upper or second compartment of thecolumn. The reverse loop will be described in greater detail below andespecially in FIGS. 10-13. Typically a pump or other like device is usedfor establishing this reverse circulation (see FIGS. 3A and 10-13). Asis discussed in greater detail below, the reverse circulation of aqueousmedium results in the removal of particulates from the column, thecleaning of debris caught within the divider/screen 128/112 and 123/111of the column 100 and the capacity to allow particulates through thecolumn in a non-concentrated, dilute manner, thereby eliminating theneed for disposal of concentrated particulates.

FIGS. 3A and 3B show cross sectional views of a purging column 100 inaccordance with embodiments of the present invention. FIG. 3A provides acolumn in absence of adsorption material, and FIG. 3B provides the sameview but with each compartment 108, 110 within the column 100 packedwith an appropriate amount of adsorption material 124. Each column showsa reverse loop 122 for reversing the circulation of aqueous mediumwithin the column. Under normal operating conditions, aqueous mediumenters the column 100 via an inlet 114 on an input end 102 of thecolumn. A distribution pipe 126 delivers the aqueous medium to a pointbelow a screen 111 and divider 123. A second screen 112 and divider 128separates the column into two compartments 108, 110. One end 125 of thedistribution pipe 126 is also adapted to support the second divider 128within the column. Column outlets 116 are shown from the secondcompartment 110 of the column. A pressure release provides release ofunacceptably high levels of pressure from the column.

A reverse loop 122 having a pump 130 for circulating aqueous medium fromthe first compartment 108 to the second compartment and back to thefirst compartment 108. As will be discussed in greater detail below, thereverse loop 122 provides an integrated loop for unclogging/purgingclogged adsorption material and screen/divider 112/128 and 111/123within the column 100 and release particulates with the discharge of thetreated aqueous medium through the outlet 116. The pump circulates theaqueous medium from the first compartment 108 to one or more exteriorreverse loop pipes 134 to the distribution pipes located above thedivider at the output end of the column. The aqueous medium is thenpushed via the pump and gravity back through the second compartment 110and to the first compartment 108. Note that the column is closed off bya shut off valve (not shown), so that the aqueous medium does notback-wash out of the column through the inlet 114.

FIG. 4 illustrates a view along line 4-4 of FIG. 3A. The reverse loop122 in the purging column 100 is connected to a series of pipes 132 (forexample 3 pipes) that extend across the diameter of the column at theoutput end 104 of the column. At the opposite side from the outlet, thereverse loop pipes 134 can connect to the series of pipes 132 or becapped off. As such, the pipes 132 act to receive aqueous medium beingreversed in direction and used in the reverse loop 122 to removeparticulates from the adsorption material and clean the divider 128 and123 and screens 112 and 111 (discussed in more detail below). The pipes132 can define openings 134 throughout for discharging medium back intothe second compartment 110 via the screen 135. Note that otherconfigurations for an outlet are considered within the scope of thepresent invention, including one or more outlet pipes, a flat dividerand an outlet, etc.

In general, a screen 135 is positioned across the top portion of thesecond compartment 110 but at or below the location of the outlet 116.Screen 135 may optionally be coupled to a divider. Adsorption material124 is typically limited from passing through the screen 135, therebyeliminating the need for a screen on the outlet pipes. At the same time,aqueous medium and particulates are able to freely pass through thescreen 135 and are thereby discharged out the outlet pipes with alimited amount of adsorption material.

FIG. 5A is a top view of a divider 128 and screen 112 for support ofadsorption material 124 within a purging column 100. The divider 128provides a series of protected openings 136 (see FIGS. 5B, 6 and 7) forpassage of aqueous medium through the divider 128, while acting as aplatform or support to carry the weight of any settled adsorptionmaterial 124. Divider 123 and screen 111 have the same properties asdivider 128 and screen 112. In various embodiments, screens 111 and 112are provided without one or both of the dividers 123 and 128.

Orientation of the protected openings 136 through the divider 128 isshown especially well in FIGS. 6 and 7. The screen 112 limits the backmovement of the adsorption material 124 with gravity back through theopening 136. A raised deck 140 overlaps each opening 136, providing aspace between the raised deck and platform. The deck provides protectionfrom the bulk of the adsorption material moving through the opening,especially when the purging column is not operating in the normal orup-flow direction, where aqueous medium moving through the divideropenings generally moves the adsorption material away from the top sideof each divider. The raised deck can be supported by a series of columns142 or by a cylindrical screen or mesh (not shown).

Note that the specific gravity of the adsorption material is consideredwhen designing a purging column of the present invention. As can be seenfrom FIGS. 5B, 6 and 7, the divider of the present invention limit butdo not prevent the passage of adsorption material that is pressedagainst the bottom side of the divider during normal operatingconditions. In typical embodiments, the adsorption material has aspecific gravity that causes the adsorption material to suspend in theaqueous medium during normal up-flow conditions, but settle faster thanparticulates when the up-flow is shut down. Preferably, the adsorptionmaterial is substantially packed against a divider at the output end ofeach compartment 108, 110 within the column during normal up-flowconditions.

FIG. 8 provides an illustrative view of a distribution pipe 126 forinput of the aqueous medium below a divider 128 and screen 112 and intoa first compartment 108 of the purging column 100. The distribution pipe126 has a generally cylindrical shape and a series of longitudinal slots144 formed therethrough for release of the aqueous medium into a thirdcompartment 146 formed between the divider and compartment wall. Inaddition, the pipe 126 defines a series of notches 148 at the pointwhere the distribution pipe 126 meets the bottom plate 150 of the column100 to provide further ingress points of aqueous medium into thecompartment 146 below the divider. The aqueous medium moves uniformlyfrom this pre-adsorption material compartment 146 through the divideropenings 136 and into the first compartment 108, the first compartmenthaving an appropriate amount of adsorption material for removal of atarget contaminate.

Method for Purging Particulates from an Absorption Material Constrainedin a Column

The present invention provides methods for purging particulates from anadsorption material that are contained within a column. Purging of theadsorption material facilitates the removal of particulates from withinthe adsorption material and thereby reduces or eliminates back-pressurefrom within the column. The column purge results in the absorptionmaterial being cleared of some or all of the particulates, therebyunclogging the adsorption material and returning the column to normalup-flow pressures and conditions, i.e., reduces built-up back pressurethat results from particulates within the aqueous medium clogging theadsorption medium. In addition, release of clogging particulates can beaccomplished in small enough intervals to allow for direct release withthe discharge of the treated aqueous medium and typically eliminates theneed for separately disposing of the concentrated particulates.

As such, methods of the invention provide a time and cost effectivesolution to limiting or eliminating back-pressure that builds up in acolumn used to remove contaminates from an aqueous medium. In addition,methods of the present invention allow for the removal of particulatesinto a treated aqueous medium discharge stream and avoids manuallycollecting and disposing of the same particulates that have concentratedwithin the adsorption material of the present invention. Finally, themethods of the invention provide a cleaning process for clearing theopenings within the dividers of built-up materials.

FIG. 9 provides an illustrative flow chart of one embodiment for purginga column in accordance with the present invention. A column is providedhaving a reverse loop as described above (see FIGS. 1-8). As an initialdetermination, a user determines the type of adsorptive material thatbest suits the removal of a target contaminate from an aqueous medium ofinterest 152. For example, where removal or uranium from a ground watersource is a concern, a user may determine to use a specific strong baseanion exchange resin known to be useful for removing uranium under theground water pH, salinity and the like conditions. Once an adsorptionmaterial has been identified, the user determines what amount ofadsorption material, column diameter and number of columns should beused for treatment of the particular aqueous medium of interest 154.Columns are packed with the appropriate amount of adsorption material ofinterest 156. Preferably, columns are packed with an amount ofadsorption material required for treatment of the levels/flow rate ofaqueous medium and contaminate at the treatment site.

Once the column(s) of the present invention are ready for use, aqueousmedium is passed through the columns at a starting flow rate 158. Theaqueous medium is typically passed through the column in an up-flowdirection. Typical flow rates for a drinking water source at start up isfrom about 3 to 15 gpm/ft². The back-pressure of the start-up flow ismonitored 160. Given the column diameter and length, flow rate,adsorption material and bed size, an upper amount of back-pressure isdetermined. Note that the up-flow rate and adsorption material densityand sedimentation parameters cause the adsorption material to form apacked bed at the output end of each compartment within the column,i.e., at the end of the compartment where the adsorption material ismost influenced by gravity.

The column is monitored and back-pressure considered until theback-pressure in the column is unacceptably close to the determinedthreshold value 162. Once a determination has been made, either manuallyor automatically, the up-flow of aqueous medium is stopped for a periodof at least 30 seconds. During the shut-down time, the adsorption mediumis allowed to settle through the aqueous medium in each compartment ofthe column 164. The settling of particulates and adsorption materialwithin the aqueous medium is determined by the settling velocity or fallvelocity of the sediment. In typical embodiments of the presentinvention, the particulates have a slower settling velocity and migratetoward the upper end of the settled adsorption material. A reverse flowpulse is then applied to the aqueous medium zone directly above the topof the settled adsorption material and particulate bed 166. The aqueousmedium and the top portion of the bed is pulled through the reverse loopand distributed back to the output end of the column. Typical reversepulses last from about 5 to about 15 seconds and continue to facilitatethe settling out of adsorption material and particulates into theadsorption material bed.

After from one to about five pulses, the reverse loop is stopped and theadsorption material allowed to settle 168. Note that a portion of theparticulates interspersed throughout the adsorption material have nowbeen re-distributed onto the top end (output end) of the adsorptionmaterial bed. In this manner, particulates that are generally located atthe input end of the adsorption material, and thereby clogging theadsorption material, have been re-distributed toward the output end ofthe same adsorption material bed.

The column is now re-started in the up-flow direction 170. Particulatesthat have settled out onto the top layers of the adsorption material arenow able to exit through the output end of the column (note that ascreen prevents the escape of adsorption material through the sameegress point) with the aqueous medium discharge. A filter or filters orother device may be used outside the housing to capture the particulates(see below), while the treated aqueous medium is discharged into adischarge site, e.g., into a water treatment facility.

In an alternative embodiment, the column is re-started in a variableup-flow manner 172. The variable or “slow” start is devised to graduallyexpand the adsorption material bed (input end) to the output end of thecolumn (within each compartment), where the adsorption materialultimately packs. This gradual expansion provides a period where sometrapped particulates are able to move through the adsorption materialand out of the column. Typical slow starts are performed over a periodof 0.5 to about 10 minutes and are from about 5% to about 100% thenormal flow rate of the column. A check of back pressure may then beperformed to determine the effectiveness of the adsorption materialpurging procedure 174. Assuming back-pressure has been reduced to belowthe threshold value, the column is resumed to normal up-flow operatingconditions, see arrow 176.

FIGS. 10-13 provide illustrative cross-sectional views of an operatingpurging column 100 in accordance with methods of the present invention.Referring to FIG. 10, a normal purging column receives an aqueous mediumsource (illustrated by arrow 178) at an input end 102. Dependent on thesource, a variable amount of suspended particulates 180 are within theaqueous medium, which can lead to clogging of the adsorption material124 and resulting increase in back-pressure within the column 100. Notethat the embodiment shown in FIGS. 10-13 provide stacked compartments108, 110 of adsorption material for the aqueous medium to flow through,separated by divider 128 and screen 112. The aqueous medium flowsthrough the inlet 114 and then enters a compartment 146 free ofadsorption material via a distribution pipe 126 (see arrow 182). Theflow of the aqueous medium causes the adsorption material to packagainst the divider 128 and screen 112 in a first compartment 108.Target contaminates are removed out of the aqueous medium via adsorptiononto the adsorption material, for example, uranium would be removed fromthe aqueous medium by binding to a strong-base anion exchange resin.Particulates 180 are generally trapped toward the bottom portion of theup-flow packed adsorption medium within the first compartment 108. Theaqueous medium then flows through the divider 128 and into a secondcompartment 110 having a pre-determined amount of adsorption material124 (see arrow 186).

Note that some amount of particulates 180 eventually enters into thesecond compartment 110 after navigating through the adsorption material124 (although the particulates cause clogging during the process ofmoving through the adsorption material). The aqueous medium then flowsthrough the second amount of adsorption material, which has beencompacted against screen 135 located at the output end 104 of the column100 (see arrow 190). The aqueous medium continues into the outlet pipes132 and out the outlet 116. Again note that particulates 180 becometrapped in the adsorption material 124 of the second compartment 110.Normal up-flow continues in this manner until an unacceptableback-pressure is reached or an unacceptably high level of particulateshas accumulated in the column. Note that in an alternative embodimentnormal upflow can continue for a set duration of time. The amount oftime dependent on the history of clogging at the particular site orother like sites. In this manner, the present invention can be practicedon a column at a site for predetermined intervals of time, rather thanpredetermined levels of back pressure. Preferably, this predeterminedinterval of time is of short enough duration to keep the back pressurebelow the parameters discussed above.

When it is determined that a purging procedure of the present inventionis necessary for continued operation of the column, the up-flow of theaqueous medium is stopped to allow the adsorption material andparticulates to settle within each compartment.

FIG. 11 shows a purging column 100 after the up-flow is stopped allowingthe adsorption material 124 and particulates 180 to settle within thefirst 108 and second 110 compartments. Adsorption material 124 settlesat a faster rate than the suspended particulates 180, facilitatingparticulate 180 movement toward the top end 192 of the adsorptionmaterial 124, and in some cases to be suspended above the adsorptionmaterial 194. Note that the heavy concentration of particulates at thebottom of the adsorption material in the first compartment hasessentially been moved in a direction toward the top end 192 of theadsorption material within each compartment.

FIG. 12 shows the reverse flow (as shown by directional arrows 196) ofthe aqueous medium from the first compartment 108 into the secondcompartment 110 and back into the first compartment 108. The aqueousmedium is moved from a zone 198 above the settled adsorption material inthe first compartment 108 to the outlet pipes 132 above the adsorptionmaterial in the second compartment 110 and back to the first compartment108 through screen 135 and the adsorption material constrained withinthe second compartment 110.

Particulates 180 suspended in the zone 198 above the adsorption materialin the first compartment 108 generally are moved to the secondcompartment 110 and adsorption material in both compartments areagitated so as to allow suspended particulates 180 to move toward thetop end of the adsorption material (via settling properties of theparticulates within the aqueous medium). The reverse flow concentratesthe particulates 180 toward the top end of the adsorption material 124in each compartment, and especially in the second compartment 110. Inaddition, the reverse flow pushes adsorption material caught in screens111, 112 and 135) back into their respective compartments, therebyserving as a screen cleaning step as well. Reverse flow pulses can lastfor an amount of time sufficient to disturb and move particulates 180 tothe top end of the second compartment 110, but are generally about 10seconds to 120 seconds in length. Typical reverse flow rate is about 10to 90% flow rate of the normal up-flow rate, and preferably about ¼ ofthe up-flow rate. During a reverse flow pulse, the normal up-flow intothe column remains stopped and a check valve located at the inlet isclosed to prevent back-flow of the aqueous medium out of the column.

FIG. 13 shows the resumption of normal up-flow through the purgingcolumn 100 once the stop and reverse flow of the aqueous medium iscomplete (see FIGS. 10-12). Note that portion of the particulates 180previously caught in the adsorption material 124 are now able to exitthe column 100 through an outlet 116 at the top end of the secondcompartment. Also note that particulates continue to enter the columnvia the inlet 114 and that not all particulates are moved through thesystem on any one purging procedure, rather the purging substantiallyreduces the number of particulates clogging the adsorption material.

In alternative embodiments, the outlet 116 of the purging column isfluidly connected to a filter 200 adapted for the removal of theparticulates, although some embodiments envision that the particulatesare simply released back into normal use of the aqueous medium or aredumped into a sewer or other like disposal site.

Further, and as previously described, resumption of up-flow into thepurging column can be performed using a “slow” start. Slow startsgradually move the adsorption material and particulates toward theoutlet portion of the column, allowing the particulates, typicallyhaving slower settling rates, to move out of the column before theadsorption material becomes packed against the dividers in the upwarddirection. Typical slow starts are performed by running the aqueousmedium through the column at from about 5% to 100% of the normal flowrate. The slow start typically last from about 1 to about 15 minutes inlength or until the particulates in the upper compartment have had anopportunity to move out of the column.

System for Removing Contaminates from an Aqueous Medium

Embodiments of the present invention provide systems for the removal ofcontaminates from an aqueous medium. In one embodiment, a purgingcolumn(s) 100 of the present invention is connected to an aqueous mediumsource 202 and discharges the aqueous medium into a suitable dischargerepository, for example a sewer or the like 204. The purging columns 100can be connected in series (side-by-side or vertically stacked) or inparallel. A filter or filters 206 can be incorporated into the dischargestream to limit or eliminate particulates where appropriate.

Referring to FIGS. 14A and 14B, a two compartment column 100 (verticallystacked) (14A), and in series (side-by-side 208, 210) (14B) are shown.With regard to FIG. 14A, the second compartment 110 of the column 100does not have an upper screen, but rather, optional screens and filterconnected to the column (the column may also have a screen integratedwithin the second compartment as shown in FIGS. 10-13).

Aqueous medium is received from a source 202, e.g., a deep well pump,and delivered to the column in an up-flow direction. Adsorption materialis constrained within each of the two compartments 108, 110.Contaminates within the aqueous medium are substantially removed and theaqueous medium is discharged via screened or unscreened column outlet116. A series of one or more safety filters 206 can receive thedischarged aqueous medium for elimination of free adsorption materialand/or particulates. A safety filter separates the filtered aqueousmedium from the particulate containing discharge, with the filtered andtreated aqueous medium going to a distribution 224. A bag filter 208 canthen receive the particulate containing filtered aqueous medium toensure the removal of most particulates and adsorption material from thetreated aqueous medium.

A series of one or more check valves 210 can be utilized on the inlet114 of the column to minimize back-flow out of the column, especiallywhen the adsorption material within the column is undergoing a purgecycle using a reverse loop of the invention. A control panel 212 canmonitor flow rate, back-pressure, feed and discharge levels ofcontaminate, safety filter condition, and when to take samples.

In one embodiment, as shown in FIGS. 14A and 14B, a portion of thereleased discharged aqueous medium is released into a drain, e.g., asewer system 204. Filtered aqueous medium having minimal amounts ofparticulate or adsorption material is discharged back into adistribution pathway. Note that in some systems of the presentinvention, there is no drain, so the discharged aqueous medium can bepumped back to the column or can be pumped to a storage tank for latermanual disposal (not shown). The systems of the present inventionfacilitate removal of particulate from the aqueous material and minimizethe build-up of back-pressure within the system.

A system bypass 214 allows the systems of the present invention to beisolated for maintenance or where the process is not required, i.e.,when the feed does not have a sufficient level of a contaminate tonecessitate removal via the adsorption materials of the presentinvention. It is also noted that the column 100 has a series ofadsorption material add 216 and removal 218 ports, as well as a columndrain port 220. The system also includes a system air release 222 tominimize air within the distribution lines. Finally, as briefly notedabove, treated and filtered aqueous medium is provided back to adistribution point 224.

FIG. 15 provides a side view of a two column system in accordance withthe present invention. Two purging columns 208, 210 are connected inseries, each column having one compartment 226 for constraint ofadsorption material. Note that each of the columns 208, 210 couldinclude two or more compartments for constraint of separate portions ofadsorption material, as is discussed in greater detail above. A reverseloop of the present invention can also be incorporated into each of thetwo columns (one compartment each) to enhance reduction of particulatesfrom the adsorption material. In such instances, the reverse loop wouldoperate as above for the two compartment column, but would move aqueousmedium from just above the bed volume of adsorption medium, when thecolumn is in a stop or stand-down status, to above the divider at theoutput end of the column, as described above. The principles involved inmoving particulates from the input end of the column to the output endof the column would be the same. A filter between columns can beincluded. FIG. 16 shows a perspective top view of the two column system,including a top view of a reverse loop on each column.

Having generally described the invention, the same will be more readilyunderstood by reference to the following examples, which are provided byway of illustration and are not intended as limiting.

EXAMPLES Purging Column Limits Particulate Build-Up in Uranium RemovalSystem

A uranium removal system was prepared for treatment of an aqueous mediumsource located in Dinwiddie, Va. The system was tested for the abilityto treat and process a continuous flow of water for the removal ofuranium. A pair of single stage, fluidized bed vessels rated for 150pounds/in² operating pressure were provided to the Dinwiddie drinkingwater supply. The vessels were designed to handle: 80 gallons per minute(gpm), having approximately 80 ppb uranium, and an empty bed contacttime of 3.7 minutes at a hydraulic loading rate of 8.3 gallons perminute per square foot. The vessels were connected to each other inseries and both had an up-flow design, see FIGS. 1-8.

In general, the systems of the present Example include Schedule 10 304Lstainless steel piping designed to permit feed, discharge and bypasspiping connections into the distribution system. The pipe was flangedand welded as required for each connection.

A bypass pipe, and necessary valves, was included in the system topermit the allow for isolation of the uranium removal vessels from theDinwiddie water supply. The system included feed and discharge valves,air-release valves, bypass valves, a hydraulically actuatedslow-operating check valve, pressure relief valves and a containmentfilter. The containment filter was stainless steel and fitted with areplaceable filter element and differential pressure switch.

The system included a totalizing flow meter with a local display. Thepressure gages were provided for system feed, treatment vessel dischargeand system discharge. The pressure gage piping was NPT stainless steeland included a root valve for isolation.

The operation of the uranium removal system was fully automated andrequired little to no operator activity. For operation of the system ofthe current Example, the following operating sequence was followed:

1. The target deep well pump is started from the customer controlsystem, causing water to flow the pipe network. Entrained air is bledthrough automatic vent valves.

2. Slow-operating check valve opens based on system hydraulic pressure,allowing water flow to enter the treatment vessels.

3. The adsorption material was expanded in an up-flow direction anduranium adsorbed to the adsorption material.

4. A flow meter records the number of gallons treated.

5. The contaminate filter was manually cleaned when required.

6. Purging methods of the present invention were performed periodicallyto facilitate flow through of particulates out of the constrainedadsorption material.

Note that the NSF approval of the adsorption material was maintainedunder NSF Standard 61.

In more detail, an uranium removal system was installed having twoup-flow tanks operated in series, each tank having approximately threefeet of uranium removal adsorption material. The feed water, while lowin suspended solids or particulates (2.5 NTU) contained sufficientparticulates to cause plugging of the adsorption material over time. Thecapacity of the system was approximately eighty gallons per minute. Flowrates for the system were selected to achieve a semi-packed bed in theup-flow configuration at four to ten gallons per square foot per minute(actual design parameter is 8.3 gpm/ft²). Embodiments of the presentinvention, including a reverse loop and a slow opening check valve wereinstalled on each of the two tanks. A rinsing time of 45 seconds was setfor the entirety of the run. In addition, approximately five stop andstart-up procedures were performed each. Data in Table 1 illustrate thepressure and particulate amounts for the system over a period of about250 days.

TABLE 1 ~pounds Feed Discharge Delta Gallons particulates Day EventPressure Pressure Pressure Treated in feed 1 start 59 61 2 10 0 20sample 58 62 4 627,900 26 56 sample 60 62 2 1,481,500 61.4 84 sample 5963 4 4,320,620 179 117 sample 60 62 2 5,030,400 209 231 sample 60 63 36,824,700 283

The data from the current example shows that over a 250 day period ofrunning, little to no pressure built-up in the adsorption material andapproximately 283 pounds of particulates were collected and removed outof the system. In this particular case the particulates were removedfrom the system into a filter and the filter material disposed of at anapproved site. This provided a significant cost (no concentratedparticulate disposal cost) and time (no shut down to back-wash thesystem) benefit

It is understood for purposes of this disclosure, that various changesand modifications may be made to the invention that are well within thescope of the invention. Numerous other changes maybe made which willreadily suggest themselves to those skilled in the art and which areencompassed in the spirit of the invention disclosed herein and definedin the appended claims.

The specification contains numerous citations to patents, patentapplications, and publications, each is hereby incorporated by referencefor all purposes.

1. A housing comprising: a compartment for constraining an adsorptivematerial, the compartment having an input end, a middle portion and anoutput end, wherein the compartment is adapted for an aqueous medium toflow through the input end, the middle portion and exit out the outputend; a screen or other sieve device that covers the output end of thehousing for preventing release of adsorptive materials out of thecompartment with the aqueous medium; and a reverse loop adapted toreceive and transport aqueous medium and adsorptive material from withinthe middle portion of the compartment and distribute to the output endof the compartment, wherein the aqueous medium and adsorptive materialthen re-circulates back to the middle portion of the compartment;wherein the housing is adapted to receive the aqueous medium at theinput end and release aqueous medium through the output end and out anoutlet in an up-flow direction and wherein the reverse loop is adaptedto reverse the direction of flow within the housing to move the aqueousmedium from the output end of the compartment and back toward the middleportion of the housing and thereby circulate the aqueous medium back tothe outlet end to provide a purging of the adsorptive material.
 2. Thehousing of claim 1 wherein the housing is a column having a diameter ofat least 1 ft.
 3. The housing of claim 1 wherein the adsorptive materialis an anion exchange resin.
 4. The housing of claim 1 wherein thereverse loop has one or more exterior pipes for moving the aqueousmedium from the middle portion of the housing to the outlet end of thehousing.
 5. The housing of claim 4 wherein the reverse loop comprises apump or other like device for moving the aqueous medium from the middleportion to the exterior pipes to the outlet end of the housing toestablish the reverse circulation with the housing.
 6. A system forremoving a contaminate from aqueous medium, the system comprising: ahousing having an internal volume for constraining an adsorptivematerial, the adsorptive material taking up a portion of the internalvolume wherein the column is adapted to receive and expel the aqueousmedium in an up-flow direction; a reversal loop operatively connected tothe housing for purging the adsorptive material within the housing; aseries of filters operatively connected to the housing for capturingexpelled particulates and adsorptive material from the housing; whereinthe particulates and adsorptive material are returned to the housing andthe aqueous medium is discharged from the system as a treated aqueousmedium.
 7. The system of claim 6 further comprising a control panel formonitoring pressure within the housing and activating the reversal loopon the housing to facilitate the purging of the adsorptive materialwithin the housing.